Susan finds an alien artifact in the desert, where there are temperature variations from a low in the 30s at night to a high in the 100s in the day. She is interested in how the artifact will respond to faster variations in temperature, so she kidnaps the artifact, takes it back to her lab (hotly pursued by the military police who patrol Area 51), and sticks it in an "oven" -- that is, a closed box whose temperature she can control precisely. Let T(t) be the temperature of the artifact. Newton's law of cooling says that T(t) changes at a rate proportional to the difference between the temperature of the environment and the temperature of the artifact. This says that there is a constant k, not dependent on time, such that Tâ²=k(EâT), where E is the temperature of the environment (the oven).

Before collecting the artifact from the desert, Susan measured its temperature at a couple of times, and she has determined that for the alien artifact, k=0.6. Susan preheats her oven to 90 degrees Fahrenheit (she has stubbornly refused to join the metric world). At time t=0 the oven is at exactly 90 degrees and is heating up, and the oven runs through a temperature cycle every 2pi minutes, in which its temperature varies by 35 degrees above and 35 degrees below 85 degrees.

Required:
a. Let E(t) be the temperature of the oven after t minutes.
E(t) =

b. At time t = 0, when the artifact is at a temperature of 40 degrees, she puts it in the oven. Let T(t) be the temperature of the artifact at time t.
Then T(0) =